Process for producing sintered iron ore product

Abstract

PCT No. PCT/JP93/01230 Sec. 371 Date Apr. 29, 1994 Sec. 102(e) Date Apr. 29, 1994 PCT Filed Aug. 31, 1993 PCT Pub. No. WO94/05817 PCT Pub. Date Mar. 17, 1994.The present invention relates to a method for sintering an iron scrap in a process for producing a sintered ore which is used as a raw material in ironmaking in a blast furnace. Zn contained in the iron scrap is removed in the step of sintering to enable a light-weight iron scrap to be used in a large quantity in the blast furnace and, at the same time, to enhance the yield of sintered ore in the step of sintering. In the production of a sintered ore as a raw material for use in a blast furnace by using a Dweight-Lloyd sintering machine, a mixture obtained by mixing a fine debris of an iron scrap with a raw material for a sintered ore is placed on a pallet to produce a scrap-bearing sintered ore. The mixture may be incorporated in a packed bed in its entirety, in its upper bed alone or in its lower bed alone. The iron scrap is fixed to the sintered ore and used as a material for use in a blast furnace. Further, the amount of coke used as a heat source can be reduced, which contributes a reduction in occurrence of CO2 and NO2 derived from combustion of coke.

We claim: 
     
       1. A process for producing a sintered iron ore product comprising sintered iron ore material and unmelted iron scrap, said process comprising the steps of: in the production of a sintered iron ore using a downward suction sintering machine, either adding an iron scrap to a raw sintering iron ore to provide a raw mix which is placed on a pallet to form a packed bed or alternatively placing a raw mix of an iron scrap with raw sintering iron ore material on a pallet to form a packed bed; and igniting the surface of the packed bed to effect sintering, wherein said raw mix of an iron scrap with a raw sintering iron ore contains an iron scrap in a thin debris or lump form and a flux with the proportion of the flux to the total amount of said iron scrap in a thin debris form and said flux being in the range of from 1 to 30% or the proportion of the flux to the total amount of said iron scrap in a lump form and said flux being in the range of from 30 to 70%, and wherein 0.5 to 100% of said iron scrap remains unmelted during said sintering. 
     
     
       2. A process for producing a sintered iron ore product using iron scrap as a raw material according to claim 1, wherein said scrap contains an iron scrap in a thin debris form having a maximum thickness of not more than 5 mm and a maximum length of not more than 50 mm or an iron scrap in a lump form having a maximum thickness of not more than 10 mm and a length of not more than 150 mm. 
     
     
       3. A process for producing a sintered iron ore product using iron scrap as a raw material according to claim 1, wherein in said packed bed, said raw mix provided by adding an iron scrap to a raw sintering iron ore product in an amount up to 100% based on the total amount of the iron scrap and the raw sintering ore is packed on the top surface of a packed bed not containing an iron scrap on said pallet so as to occupy 50% or less of the total thickness of the packed bed. 
     
     
       4. A process for producing a sintered iron ore product using iron scrap as a raw material according to claim 1, wherein in said packed bed, said raw mix provided by adding an iron scrap to a raw sintering iron ore product in an amount up to 100% based on the total amount of the iron scrap and the raw sintering iron ore product is packed on the underside of a packed bed not containing an iron scrap on said pallet so as to occupy 50% or less of the total thickness of the packed bed. 
     
     
       5. A process for producing a sintered iron ore product using iron scrap in a thin debris form as a raw material according to claim 1, wherein said iron scrap comprises an iron scrap in a thin debris form having a maximum thickness of not more than 5 mm and a maximum length of not more than 50 mm and is mixed in an amount of 100% based on the total amount of said iron scrap in a thin debris form and said raw sintering iron ore product. 
     
     
       6. A process for producing a sintered iron ore product using iron scrap in a lump form as a raw material according to claim 1, wherein said iron scrap comprises an iron scrap in a lump form having a maximum thickness of not more than 10 mm and a maximum length of not more than 150 mm and is mixed in amount of 70% or less based on the total amount of said iron scrap in a lump form and said raw sintering iron ore product. 
     
     
       7. A process for producing a sintered ore using iron scrap as a raw material according to claim 1, wherein in the stage of sintering said packed bed, the amount of coke added is increased to provide within the resultant sinter bed such gas atmosphere conditions that the CO to CO 2  partial pressure ratio is 0.15 or more.